/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/runtime/runtime.h"

/**
 * Advises kernel about memory intentions, the POSIX way.
 *
 * @return 0 on success, or errno on error
 * @raise EINVAL if `len` is zero
 * @raise EINVAL if `advice` isn't valid
 * @raise EINVAL if `addr` isn't multiple of `sysconf(_SC_PAGESIZE)`
 * @raise ENOMEM if interval overlaps unmapped pages
 * @returnserrno
 */
errno_t posix_madvise(void *addr, size_t len, int advice) {

  if ((int64_t)len <= 0)
    return EINVAL;

  if ((uintptr_t)addr & (__pagesize - 1))
    return EINVAL;

  int err;
  if (!IsWindows()) {
    int e = errno;
    err = sys_madvise(addr, len, advice);
    if (err == -1) {
      err = errno;
      errno = e;
    }
  } else {
    err = sys_posix_madvise_nt(addr, len, advice);
  }

  return err;
}
